Scalable Solar Evaporator Based on Bandgap Engineered CuMnCrO ₄ Spinel Oxide with Salt‐Resistant Property for Contaminated Seawater

Abstract

Abstract Freshwater scarcity demands innovative solutions that combine efficiency, durability, and scalability. Here, CuMnCrO 4 (CMCO), is presented as a ternary spinel oxide photothermal absorber introduced for the first time in solar desalination, synthesized via co‐substitution of Mn 3 O 4 with Cu and Cr. This multi‐cation design narrows the bandgap from 2.3 to 1.49 eV, markedly enhancing solar absorption across the visible and near‐infrared spectrum and enabling efficient light‐to‐heat conversion. Unlike conventional carbon or single‐oxide‐based systems, CMCO demonstrates record‐high evaporation performance of 4.1 kg m −2 h −1 under 1‐sun, positioning it among the most efficient oxide‐based ISSG materials reported to date. Equally novel is the integration of CMCO with a cotton fabric substrate and hydrophobic polyester strips in an inverted U‐shaped configuration, which ensures continuous water wicking, localized salt separation, and mechanical robustness. This architecture delivers stable operation over three weeks without salt accumulation, overcoming a long‐standing challenge in ISSG. Furthermore, the system retains high efficiency under strongly acidic/alkaline conditions and in oil‐ or dye‐contaminated water, demonstrating unique resilience rarely reported in solar desalination systems. Finally, the modular design enables straightforward scalability from laboratory‐scale strips to large‐area panels. Together, these advances establish CMCO‐based systems as a new materials platform for practical, durable, and scalable solar desalination, offering a sustainable pathway toward addressing global water scarcity.